You'll need to compare buying regular ticket with a pass and reservations. Regular tickets have dynamic prices, so you need to look up prices for your dates and times.

Look here for prices of regular tickets:

Florence to Zurich: www.trenitalia.com (pass reservation €13+€13 for the journeys with 1 change)

Zurich to Paris: www.sncf-connect.com (pass reservation €29 in 2nd class, €39 in 1st)

Paris to Barcelona: www.sncf-connect.com (pass reservation €35)

Pass reservations can be booked here: raileurope.com. There are ways to spend less on pass reservations, but journeys will take a bit more time then.

Thank you very much for your response. So I’m a bit confused because I was originally going to purchase the Global Pass for 5 days but was told by a user in the Community that I should not buy one because I would only be traveling less days. So I went to try and purchase. But now I’m reading that I need to buy a Global Pass again. Is it because I’m coming from the United States? Do I need the pass? I appreciate the information

As I tried to explain, you can also travel on regular tickets instead of with a pass. But whether that will be cheaper, we can't tell you because only you know when you want to travel.

The pass price to compare with should be a global 4-day pass, plus the reservations that I mentioned in my previous post. You'll only need it on 3 days, so you'll have one day to spare.